Paperboard interlock arrangement

ABSTRACT

An interlocking paperboard carton blank (10) is disclosed. The carton blank has at least one flap (19) projecting from a side dge of a first base panel (14), the flap having a leading portion (20) which is folded about a scored waist section score line (23) back onto the remainder of the flap to double the thickness of the flap. The leading portion of the flap includes at least one, and preferably two laterally projecting portions (21). The flap is inserted folded end first into at least one correspondingly positioned opening (27) defined in a second base panel (15) of the carton blank. The flap is passed into the opening until the two lateral projections of the folded flap are passed through the opening in the second base panel, whereupon the laterally projecting portions are constructed and arranged to be urged upwardly from the remainder of the flap so as to prevent withdrawal of the flap from the opening while the leading portion of the flap remains folded against the remainder of the flap to ensure that the flap has a doubled thickness in the interlocked base panels of the carton blank.

This invention relates to interlock arrangements between two pieces ofpaperboard. In particular, but not exclusively the invention relates tosuch arrangements for securing the ends of a paperboard sleeve about anarticle or articles.

BACKGROUND OF THE INVENTION

According to the present invention an interlocking arrangement isprovided for connecting the two end pieces of a paperboard carton blankhaving at least one flap projecting from a first one of the end piecesfor cooperation with at least one respective opening defined in a endsecond end piece, of the paperboard carton blank the flap or flaps eachhaving a leading portion spaced farthest from the remainder of the firstend piece of the carton blank, behind which leading portion is a portionwhich projects laterally at least in one direction, the flap or flapseach being folded such that the leading portion and the laterallyprojecting portion are folded back on the rest of the flap, the flap isthen inserted into its associated opening within the folded area orareas of the second piece first, so that when the laterally projectingportion of the flap passes through the opening it takes up a positionclear of the edge of the opening, thereby preventing withdrawal of theflap while the leading portion thereof remains held by the opening. Suchan interlocking arrangement can lie generally flat relative to thepieces of paperboard.

Preferably each flap has portions projecting laterally in bothdirections, the flap having a waisted section immediately behind theprojecting portions, at which waist the flap is folded back along astraight line.

In preferred embodiments the opening comprises a single cut having twoends.

With chosen arrangements the laterally projecting portions are angledinto the waist and into the leading portion. Also the maximum widthacross the laterally projecting portions of each flap is substantiallythe same as the maximum width of the associated opening. It is apreferred feature that the ends of the opening cut are angled in amanner corresponding to the angling, when folded back, of the laterallyprojecting portions towards the leading portion.

Preferably the flaps are dimensioned in such a way that during insertionof the leading portions do not clear the edges of the openings definedin the second end piece of the carton blank.

In certain embodiments the two pieces of paperboard are constituted byends of a wraparound sleeve for containing one or more articles.Preferably two or more flaps are provided on one end of the sleeve andtwo or more corresponding openings are provided on the other end of thesleeve.

One preferred feature is that the ends of the openings are aligned on afold line such that the free portion of the sleeve end hinges about thefold to in assist in the insertion of the flaps.

Another feature is that the fold comprises two end sections joined by aC-shaped cut extending away from the leading portion of the flap so thatwhen folded back, a tab projects forwardly of the fold line.

Embodiments of the present invention will now be described in moredetail in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a plan view of a carton blank incorporating an interlockingarrangement according to the present invention.

FIGS. 2a and 2b show sequential perspective end views of theinterlocking arrangement of FIG. 1 before and after connection.

FIG. 3 is a cross-sectioned plan view of an assembled interlockingarrangement.

FIG. 4 is a partial schematic end view of the assembled interlockingarrangement of FIG. 3,

FIG. 5 is a plan view of a second carton blank incorporating anotherinterlocking arrangement according to the present invention.

FIGS. 6a and 6b show sequential perspective end views of theinterlocking arrangement of FIG. 5 before and after connection.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIGS. 1 to 4 there is shown a carton blank 10 for forming asleeve-like carton for retaining three articles. The blank 10 has a toppanel 11, main side panels 12, secondary side panels 13, a first basepanel 14 and a second base panel 15. Cutouts 16 are provided in the toppanel for locating the tops of the articles and cutouts 17 are providedin the secondary side panels for locating the bottoms of the articles.These features are well known in the art of carton manufacture.

The first base panel 14 is hingedly connected to its associated sidepanel 13 by means of a fold 18 which connects the ends of the cutouts17. The base panel 14 is formed with three projecting flaps 19 eachhaving a leading portion 20. Immediately behind the leading portions, onthe side nearest the cutouts 17, are laterally projecting portions 21which are angled laterally outwards at 22 from a waist section 23 in theform of a fold. Behind the waist, at 24, (FIG. 1) the flap again flareslaterally towards the widest parts 25 of the flap 19. The widest parts25 are just further from the waist 23 than are the widest parts of thelaterally projecting portions 21, but are of a similar lateral width.

The second base panel 15 has a fold 26 interspersed with three openings27 in the form of cuts. The openings 27 are located at positions whichcorrespond to the positions of the flaps 19 on the first base panel 14when the blank 10 is folded to make the carton. The lateral ends 28 ofeach opening 27 are angled towards the free edge 29 of the base panel 15in the inward direction and then angled back toward the central portion30 which lies along to the imaginary continuation of the fold 26. Thelateral width of the openings are just marginally larger than the widthof the laterally extending portions 21 of the flaps 19.

The connection of the interlocking arrangement will now be described.For the sake of convenience the connection of only one flap 19/with oneopening 27 will be described. The first step is to bring the two basepanels 14, 15 towards each other. The leading portion and laterallyprojecting portions of the flap 19 are folded upwards and back on theremainder of the flap about the waist fold 23. Also the end of thesecond base panel 15 is folded up slightly about the fold 26 therebywidening the opening 27. The flap 19, fold 23 first, is then insertedthrough the opening 27 laterally projecting portions 21 are just able topass through the opening 27 and when they have cleared the angled ends28 of the opening 27 they tend to spring upwardly thus preventingwithdrawal of the flap 19 relative to the opening 27 because the leadingedges, now facing backwards, of the laterally projecting portions 21engage the angled ends 28 of the opening 27 and. At the same time thecentral portion 30 of the opening is located such that the leadingportion 20 of the flap 19 does not clear the opening 27 and remains heldbelow the second base panel 15. Further insertion of the flap is notpossible because the ends of the opening 27 engage the widest parts 25of the flap 19 at its hinged connection to the rest of the base panel14.

When the arrangement is fully interlocked the interlock is generallyflat. Such an interlock is, therefore, particularly suitable for usewith flat-bottomed articles or containers, but can be used for otherarticles or containers.

In the second embodiment shown in FIGS. 5 and 6, most features are thesame as those in FIGS. 1 to 4 and so have been given like referencenumerals. The principal difference is that the waist hinge 23 on theflap 19 is not continuous but has a C-shaped cut 50 made centrallybetween two spaced end folds 51. When the leading portion 20 is foldedback the tab 52 inside the C-shaped cut 50 projects forwardly of thehinge folds 51. When the flap 19 is interconnected with the opening 27,the tab 52 remains projecting forwardly. The article held at thelocation of the tab 52 tends to press down on the tab thereby tending toencourage the laterally projecting portions 21 to raise further so as tostrengthen the engagement with the ends 28 of the opening 27.

It will be appreciated that the shapes and dimensions discussed aboveare examples of suitable arrangements. Other pack sizes are of courseequally suitable and it is also possible that the interlock could beprovided on any paperboard article not necessarily cartons formultipacks.

While preferred embodiments of the invention have been disclosed in theforegoing specification, it is understood by those skilled in the artthat variations and modifications thereof can be made without departingfrom the spirit and scope of the invention, as set forth in thefollowing claims. Moreover, the corresponding structures, materials,acts, and equivalents of all means or step plus function elements in theclaims are intended to include any structure, material, or acts forperforming the functions in combination with other claimed elements, asspecifically claimed herein.

I claim:
 1. An interlocking arrangement for connecting a first basepanel of a wrap type paperboard carton blank to a second base panel, thebase panels being hingedly connected to the carton blank and beingspaced from and opposed to one another, said interlocking arrangementcomprising:at least one flap projecting from the first base panel forcooperation with a respective opening defined in the second base panel;said at least one flap having a leading portion spaced farthest from thefirst base panel, and at least one laterally projecting portion behindsaid leading portion; said leading portion and said at least onelaterally projecting portion of said at least one flap being folded backtogether onto a remaining portion of said at least one flap; whereinsaid at least one flap is sized and shaped so that when it is insertedinto its associated opening said at least one laterally projectingportion is passed through the opening and is moved into a position clearof the edge of the opening to prevent withdrawal of said at least oneflap from the opening while the leading portion remains held flatagainst said remaining portion by the opening.
 2. The interlockingarrangement of claim 1, wherein said at least one flap has two laterallyprojecting portions extending in opposite directions, said at least oneflap having a waist section positioned immediately behind said laterallyprojecting portions, said at least one flap being folded onto saidremaining portion along a score line at said waist section.
 3. Theinterlocking arrangement of claim 2, wherein said opening comprises asingle cut having two spaced ends.
 4. The interlocking arrangement ofclaim 3, wherein said laterally projecting portions are constructed andarranged to be angled with respect to the waist section and the leadingportion of said at least one flap.
 5. The interlocking arrangement ofclaim 4, wherein said laterally projecting portions have a width ofsubstantially the same width as said opening.
 6. The interlockingarrangement of claim 5, wherein the ends of said opening are angled in amanner corresponding to the angle of the laterally projecting portionswith respect to the leading portion when said leading portion and saidlaterally projecting portions are folded back onto said remainingportion.
 7. The interlocking arrangement of claim 6, wherein said atleast one flap is sized and shaped such that when said at least one flapis folded over onto said remaining portion and inserted into saidopening, said leading portion does not extend into said opening.
 8. Theinterlocking arrangement of claim 1, wherein at least two of said flapsare provided on the first base panel of the carton blank, and at leasttwo of said openings are provided on the second base panel of the cartonblank.
 9. The interlocking arrangement of claim 8, wherein the secondbase panel includes a free end portion hingedly attached thereto along afold line, and wherein said at least two openings are each aligned alongsaid fold line such that the free end portion of the second base panelhinges about said fold line for assisting in the insertion of the flapsinto the openings, respectively.
 10. The interlocking arrangement ofclaim 9, wherein said fold line along each of said at least two openingscomprises two spaced end sections joined by an elongate C-shaped cutextending away from said free end section for each said opening so thatwhen said free end portion is folded along said fold line, a tabprojects forwardly of the fold line for each said opening.
 11. Apaperboard carton blank for use in interlocking a wrap-type paperboardcarton into a packaging container for holding articles therein, saidcarton blank comprising:a top panel; a first side panel hingedlyconnected to said top panel, and a first base panel hingedly connectedto said first side panel; a second side panel hingedly connected to saidtop panel, said second side panel being spaced from and opposed to saidfirst side panel, and a second base panel hingedly connected to saidsecond side panel; said first base panel including at least one flapformed along a base panel side edge opposite said first side panel; saidat least one tab having:a first side edge and a spaced second side edge,both of said side edges extending away from said base panel side edgeand toward one another; a waist section extending from said first flapside edge to said second flap side edge defining a first flap sectionthereby, said waist section having a waist score line of a first flapwidth extending from said first side edge to said second side edge; athird side edge and a spaced fourth side edge extending away from saidwaist section and from one another; a leading edge extending from saidthird side edge to said fourth side edge and defining a second flapsection hingedly connected to said first flap section along said waistscore line; and a first laterally projecting portion formed along saidthird side edge and a second laterally projecting portion formed alongsaid fourth side edge, said laterally projecting portions extendingopposite of one another and defining a second flap width greater thansaid first flap width; a score line defined in said second base paneland being spaced intermediate the hinged connection of said second basepanel to said second side panel and a free edge opposite the second sidepanel; at least one slotted opening defined in said second base panelalong said score line, said opening having a width substantially thesame as said second flap width, said slotted opening being sized andshaped to receive said at least one flap therein.
 12. The carton blankof claim 11, wherein said second flap section is folded along said waistscore line over and onto said first flap section and then inserted intosaid opening.
 13. The carton blank of claim 12, wherein said second flapsection remains folded on said first flap section.
 14. The carton blankof claim 11, wherein said second flap section is folded along said waistscore line over and onto said first flap section and wherein saidlaterally projecting portions are inserted into and passed through saidopening so that said leading edge does not pass through said opening andsaid first flap section remains folded on said second flap section. 15.The carton blank of claim 14, wherein said second flap section isconstructed and arranged to be urged away from said first flap sectiononce said laterally projecting portions have been passed through saidopening for holding said at least one flap within said opening.
 16. Thecarton blank of claim 11, wherein said at least one opening comprises anelongate central portion extending at least partially along the scoreline in the second base panel, and a first and a spaced second lateralend formed at the opposite ends, respectively, of said central section,said lateral ends first being angled outwardly away from, and then beingangled inwardly toward said score line.
 17. The carton blank of claim16, wherein said at least one opening has a length from said firstlateral end to said second lateral end greater than said second flapwidth for allowing said laterally projecting portions to be passedtherethrough.
 18. A method of assembling a paperboard carton blank intoan interlocked wrap-type carton for holding articles therein, the cartonblank having a top panel, a first side panel and a spaced and opposedsecond side panel each of which is hingedly connected to the top panel,with a first base panel hingedly connected to the first side panel and asecond base panel hingedly connected to the second side panel, saidmethod comprising the steps of:folding the first base panel along afirst fold line and folding the second base panel along a second foldline; folding a first portion of at least one flap formed along a sideedge of the first base panel opposite the first side panel over onto asecond portion of said at least one flap along a waist score line;folding the second base panel along a score line so that a free end ofthe second base panel opposite the second side panel is angled withrespect to the remainder of the second base panel, and at leastpartially opening at least one slotted opening defined in the secondbase panel along said score line in response thereto, said openinghaving a width substantially the same as the width of the at least oneflap and being sized and shaped to receive said at least one flaptherein; bringing the first base panel and the second base paneltogether and inserting said at least one flap into said at least oneslotted opening; and passing a pair of opposed laterally projectingportions formed as a part of said flap and opposed to one anotherthrough said at least one opening and urging said first portion of theat least one flap away from the second portion thereof in responsethereto while holding a leading edge of the first portion of said flapfolded against the second portion of said flap, and holding the basepanels of the carton blank together in interlocked relationship inresponse thereto.